Lab mice thrive best at 30 degrees Celsius (86 degrees Fahrenheit), but temperatures in laboratories ranging between 20 and 26 degrees Celsius (68 and 78.8 degrees Fahrenheit) are often way cooler for these animals.

In a new study, researchers have shown that temperatures far below the level best for these mammals take a toll on their health. This may screw up the results of science experiments as environmental factors affect the basic biology of mice.

A growing number of evidence, which were reviewed in a research published in Trends in Cancer on April 19, shows that even mild chronic cold stress may mess up results of studies in fields that range from neurobiology to obesity.

Although the animals may still be considered as healthy at cooler temperatures, lab mice spend more energy maintaining their body's core temperature.

A few years ago, immunologist Bonnie Hylander, from the Roswell Park Cancer Institute, and colleagues started to investigate the impact of cold stress on the ability of the mouse's immune system to fight tumors.

They found that lab mice were better at fighting cancer naturally when they are warm. The animals' tumors were also observed to grow slower and were less likely to metastasize than those of the mice that were kept at standard laboratory temperatures. The warmer animals were also found to have better response to chemotherapies.

Such evidences show that the impact of cold lab temperatures on mice could cause a problem to researchers who try to track the ability of the animals to fight off a disease.

"We're concerned that too many publications in which results differ, either between labs in various countries or within the same lab, may be due to environmental conditions," said study researcher Elizabeth Repasky, from the Roswell Park Cancer Institute.

Fortunately, the researchers have proposed some ways to mitigate potential problems in mice studies that can be affected by the lab's cold temperatures.

"Right now, it would be important for researchers to be aware of the potential for data skewing and they should report the room temperature at which their mouse experiments were done," Hylander said.

The researcher added that once the room temperature appears to be a source of variability in the results of studies, researchers and journals may ask for experiments to be done at different temperatures. The outcomes can then be compared.

Another simple solution is for labs to simply raise the temperatures.